Unique Identification of Devices Using Color Detection

ABSTRACT

Methods and apparatus for uniquely identifying wireless devices in close physical proximity are described. When two wireless devices are brought into close proximity, one of the devices displays an optical indicator, such as a light pattern. This device then sends messages to other devices which are within wireless range to cause them to use any light sensor to detect a signal. In an embodiment, the light sensor is a camera and the detected signal is an image captured by the camera. Each device then sends data identifying what was detected back to the device displaying the pattern. By analyzing this data, the first device can determine which other device detected the indicator that it displayed and therefore determine that this device is in close physical proximity to it. In an example, the first device is an interactive surface arranged to identify the wireless addresses of devices which are placed on the surface.

BACKGROUND

Most computing devices have wireless capability and in order for twodevices to share data over a wireless link it is generally necessary touniquely identify the two devices and to perform a pairing operation.Wireless devices are generally identified using their wireless ID (e.g.their Bluetooth name or MAC address) and in order to pair two devices, afirst device searches for other devices which are visible over thewireless link and provides a list of possible wireless IDs to a user.The user then selects the particular wireless ID with which pairing isto occur. Dependent on the location and the range of the wirelesstechnology used, there may be large numbers of possible devicesdiscovered.

Interactive surfaces have been developed which provide a table top touchscreen by which a user can interact with a computing device. A user maywish to connect a mobile device, such as a mobile telephone, with theinteractive surface and as the interactive surfaces are touch sensitivethey can detect when a mobile telephone or other object is placed ontheir surface. However, automatic synchronization of the interactivesurface and the device can only occur if the device is physicallyaugmented with a tag (e.g. an RFID tag) because the interactive surfacecannot distinguish the device on its surface from other devices whichare discovered over the wireless link. Alternatively, the list ofdiscovered devices can be provided to the user for selection of thecorrect device (as described above) however this introduces user inputinto the synchronization process.

The embodiments described below are not limited to implementations whichsolve any or all of the disadvantages of known methods of pairingwireless devices.

SUMMARY

The following presents a simplified summary of the disclosure in orderto provide a basic understanding to the reader. This summary is not anextensive overview of the disclosure and it does not identifykey/critical elements of the invention or delineate the scope of theinvention. Its sole purpose is to present some concepts disclosed hereinin a simplified form as a prelude to the more detailed description thatis presented later.

Methods and apparatus for uniquely identifying wireless devices in closephysical proximity are described. When two wireless devices are broughtinto close proximity, one of the devices displays an optical indicator,such as a light pattern. This device then sends messages to otherdevices which are within wireless range to cause them to use any lightsensor to detect a signal. In an embodiment, the light sensor is acamera and the detected signal is an image captured by the camera. Eachdevice then sends data identifying what was detected back to the devicedisplaying the pattern. By analyzing this data, the first device candetermine which other device detected the indicator that it displayedand therefore determine that this device is in close physical proximityto it. In an example, the first device is an interactive surfacearranged to identify the wireless addresses of devices which are placedon the surface.

Many of the attendant features will be more readily appreciated as thesame becomes better understood by reference to the following detaileddescription considered in connection with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS

The present description will be better understood from the followingdetailed description read in light of the accompanying drawings,wherein:

FIG. 1 shows a flow diagram of an example method by which a firstwireless enabled device can uniquely identify a second wireless enableddevice;

FIG. 2 is a schematic diagram of a plurality of wireless enabledcomputing devices;

FIG. 3 is a flow diagram of an example method of operation of a targetdevice;

FIGS. 4 and 5 show example optical indicators;

FIG. 6 shows a schematic diagram of an interactive surface with twotarget devices on its surface;

FIG. 7 shows a schematic diagram of a synchronization pad;

FIG. 8 shows a schematic diagram of two mobile devices;

FIG. 9 shows a schematic diagram of a mobile device and a desktop PC;

FIG. 10 illustrates an exemplary computing-based device which maycomprise an initiator device;

FIG. 11 illustrates an exemplary computing-based device that maycomprise a target device;

FIG. 12 shows an example method of operation of an interactive surface;

FIG. 13 shows a method of tracking movement and/or determining userinput; and

FIG. 14 shows two example light patterns that may be displayed by theinitiator device in order to detect motion of the target device and/orto provide a user input.

Like reference numerals are used to designate like parts in theaccompanying drawings.

DETAILED DESCRIPTION

The detailed description provided below in connection with the appendeddrawings is intended as a description of the present examples and is notintended to represent the only forms in which the present example may beconstructed or utilized. The description sets forth the functions of theexample and the sequence of steps for constructing and operating theexample. However, the same or equivalent functions and sequences may beaccomplished by different examples.

FIG. 1 shows a flow diagram of an example method by which a firstwireless enabled device, referred to herein as the ‘initiator device’,can uniquely identify a second wireless enabled device, referred toherein as the ‘target device’, which is in proximity to the first devicewithout requiring the second wireless enabled device to be tagged orotherwise physically augmented. Having identified the wirelessidentifier (or address) of the target device, the initiator device canuse the wireless address to perform bidirectional communication with thetarget device over a wireless link. For example, the initiator devicemay associate (or pair) with the target device, synchronize data withthe target device or perform any other interaction with the targetdevice over a wireless link. This method can be described with referenceto FIGS. 2 and 3. FIG. 2 is a schematic diagram of a plurality ofwireless enabled computing devices 201-204 and FIG. 3 is a flow diagramof an example method of operation of the target device. The wirelessenabled computing devices 201-204 may be mobile telephones, PCs,interactive surfaces or any other kind of wireless enabled computingdevice and various examples are described in more detail below.

The initiator device 201, which comprises a light source 206 such as adisplay or one or more LEDs, detects a target device 202 in physicalproximity to the initiator device (block 101). This physical proximitydetection may be performed in any suitable way, such as by using touchsensitive technology or through user input, and various examples aredescribed in more detail below. The initiator device 201 uses itswireless transmitting and receiving modules (as indicated in FIG. 2 byantenna 206) to identify a set of nearby wireless devices (indicated bydotted line 208, block 102) which may include the target device. Thisset is referred to herein as the ‘candidate set’ and may comprise thewireless identifiers of all the devices which are within the wirelessrange of the initiator device. This process of identifying the candidateset (block 102) may use standard discovery methods, such as theBluetooth or WiFi discovery protocol, and is described in more detailbelow.

Having identified the candidate set of devices, one of which may be thetarget device 202, the initiator device displays an optical indicator,such as a light pattern (block 103) using its light source 206. Thisoptical indicator (which may be a light pattern) may use visible orinfrared (IR) light and may be any pattern, such as a single color(which may also be referred to as uniform light, e.g. an entire displayof a single color), a region of a certain color (e.g. a circle of aparticular color), a scanning light spot, a sequence of colors, apattern of varying intensity etc. The displaying of the opticalindicator (in block 103) may comprise statically displaying the samepattern all the time (as described below), displaying a single pattern(e.g. a single color or a region of color) for a period of time, ordisplaying a dynamic pattern, which changes over time (e.g. a scanningspot/lines or a sequence of colors). Where the approximate location ofthe target device is known (e.g. the position of the target device onthe touch sensitive display of the initiator device may be known), theoptical indicator (such as a light pattern) displayed may be dependentupon this location. Various examples are described in more detail below,but for the purposes of explanation only, for this example it will beconsidered that the initiator device displays a red circle on itsdisplay in the area in which the target device was detected (in block101).

The identification of the target device from the candidate set isachieved by iteratively triggering devices in the candidate set to useany light sensor 207 in the particular device to detect a signal (blocks104, 301 and 302) and to send data representative of the detected signalback to the initiator device (block 303). The devices in the candidateset may not all comprise a light sensor (e.g. device 203), but for thepurposes of this explanation the target device 202 comprises a lightsensor 207. The situation where the target device does not comprise alight sensor is described below. The light sensor 207 may be a camera, aphotodetector or any other means of detecting light incident on thedevice. Depending on the light sensor, the detected signal may comprisethe intensity and/or wavelength of the detected light or a capturedimage etc. The data representative of the detected signal which is sentto the initiator device by the target device may be the same as thedetected signal (e.g. the intensity, wavelength or captured image) orthe detected signal may be processed to generate the data representativeof the detected signal (e.g. such that the data details the colordetected and/or the time that the color was detected). Examples of thisare described in more detail below.

On receipt of the data from a device in the candidate set (block 105),the data can be used to identify whether the candidate device is thetarget device (block 106). This is achieved by using the data todetermine whether the light sensor on a particular candidate devicedetected the optical indicator (or a portion of the optical indicator)displayed by the initiator device; the target device being one which diddetect the optical indicator (or part thereof). In this particularexample, the determination can be performed through analysis of the datato determine which of the candidate set detected the red circle.

Each of the candidate set of devices may be triggered in turn (in block104) or alternatively all the candidate set may be triggeredsubstantially simultaneously and the data received from all thecandidates may be analyzed to identify the target device. Where themembers of the candidate set are triggered sequentially, the initiatordevice may stop triggering once a device is identified which detectedthe optical indicator or alternatively, the initiator device maycontinue to trigger each of the members of the candidate set. Thesequence used to trigger members of the candidate set may be set totrigger candidate devices in order of signal strength (from high to low)or based on other criteria. Examples of suitable criteria are describedin more detail below in relation to filtering the candidate set, andinclude: device class, device orientation, motion of the device andhistory of previous associations.

If there is any ambiguity in determining which of the candidate set isthe target device, (e.g. more than one device saw the red circle or apart thereof), the process may be repeated using the same opticalindicator (e.g. using the same light pattern) or a different opticalindicator displayed by the initiator device (e.g. a smaller pattern, adifferent sequence etc), until a device from the candidate set has beenuniquely identified as the target device 202. Various examples ofdifferent optical indicators are described in more detail below.

Having identified the target device (in block 106), the wirelessidentifier of the target device 202 is known and the initiator andtarget devices 201 and 202 may perform bidirectional communication overa wireless link (block 107). In an example, the most recent photographtaken by the target device may be transferred to and displayed on theinitiator device.

The identification method, as shown in FIG. 1, may be initiated by thesensing of another device (the target device) in proximity to theinitiator device (block 101) and this proximity sensing may use anysuitable technology. In an example, the initiator device may comprise aninteractive surface on which the target device is placed. In thisexample, touch sensing may be used to detect the target object on itssurface and in this example, the location of the target device on thesurface is known. Any suitable touch sensing technology may be usedwhich is capable of detecting a device placed on its surface, such asoptical touch sensing (e.g. by detecting shadows caused by objects onthe surface or by detecting light reflected back by objects on thesurface). In another example, a pressure switch, weight sensor,proximity sensor, light sensor or microphone may be used to detect whenthe target device is placed onto the initiator device (or onto aperipheral device associated with the initiator device) or otherwisebrought into proximity to the initiator device. In a further example, IRor visible emitters and receivers may be used (e.g. placed around theedge of a display) and presence may be detected when the beam from atransmitter to a receiver is broken by the presence of an object. Thisbeam-break technique may also provide approximate position informationfor the target object.

In an example, the proximity sensing may use wireless discoverytechniques. The discovery protocols may run substantially continuouslyor operate periodically to determine whether other wireless devices arein close proximity. Use of such techniques combines the proximitysensing and identification of a candidate set (blocks 101 and 102) intoa single operation.

In other examples, the method of FIG. 1 may be triggered by a user. Forexample, a user may press a button on the initiator device to initiatethe identification of a candidate set of devices (in block 102). Thisbutton may be a physical button or a soft button (e.g. on a touchsensitive display or which is pushed using a mouse). The user may,alternatively, cause the target device to emit a sound (e.g. a beep) orto vibrate and this sound/vibration may be detected by the initiatordevice.

In another example, the method may be triggered by sending a message tothe initiator device via a communication channel, such as an SMS (shortmessaging service) message. The communication channel used is adifferent channel to that which will subsequently be used for devicediscovery and pairing. In such an example, a user may send an SMSmessage (also known as a ‘text message’) from the target device to theinitiator device. This may trigger the initiator device to identify acandidate set of devices. This may be useful in some applications wherean SMS number of the initiator device is known or may be published oradvertised (e.g. for public displays). Whilst data transfer could occurbetween the initiator device and the target device using the cellularnetwork (i.e. the same network as used to send the SMS message), thiscan be expensive and may be a low data rate link. Use of a directwireless link (e.g. Bluetooth or WiFi) may be less expensive (e.g. freein many cases) and faster.

Depending on what technique is used for proximity detection or tootherwise trigger the identification of the candidate set, the initiatordevice may or may not obtain approximate location information for thetarget device. In the case of a touch sensitive display the location ofevery device on the display including the target device is known at thecandidate set selection stage. In other examples, signal strength may beused to determine an approximate location, for example signal strengthof wireless signals. WiFi or Bluetooth® signal strength may, forexample, be used where an array of access points is provided surroundingthe display. WiFi may be more appropriate for very large displays andBluetooth® for smaller displays. An array of RFID may alternatively beprovided underneath the display to detect signal strength of particularIDs. In further examples, time of flight techniques may be used toprovide an approximate location of the target device, e.g. usingacoustic, ultrasonic, radio or optical signals.

Any wireless technology may be used to identify a candidate set ofdevices and for subsequent communication with devices within thecandidate set (blocks 104, 105, 301 and 303). For example, Bluetooth,WiFi, Zigbee, X10 or any other short-range wireless communicationtechnology may be used.

As described above, the candidate set of devices (identified in block102) may comprise all those devices which are within wireless range ofthe initiator device. However, in some applications and locations thismay comprise a large number of devices, particularly where the range ofthe wireless technology used is more than a few meters. In someimplementations, the set of those devices in range of the initiatordevice may be filtered to create the candidate set. For example, the setof devices in range may be filtered according to signal strength so thatthat the devices which are furthest from the initiator device (i.e. havethe weakest signal strength) are excluded from the candidate set. Otherfilter criteria may be used, such as:

-   -   device class—for example to select only devices which are mobile        telephones. In a Bluetooth® example, each device has a device        class (type of device and services it provides) and the device        type identifier is typically retrieved during device discovery        (e.g. in block 102). The device class is separated in three        parts: the Service Class and the Major and Minor device class. A        mobile telephone will typically have a Service Class of ‘Object        Transfer and Telephony’ with a Major class of: ‘Phone’ and a        Minor class of: ‘Cellular’. In contrast a printer (which may        also be Bluetooth enabled and discovered), will have a Service        Class of ‘Rendering and Object Transfer’, a Major class of        ‘Imaging’ and a Minor class of ‘Printer’.”    -   device orientation—for example to select only devices in an        orientation which corresponds to being placed on the surface        (e.g. in a horizontal orientation, typically)    -   motion of the device—for example to exclude all devices which        are in motion    -   history of previous associations—for example the initiator        device may initially select devices which have previously        associated (or paired) with the initiator device. If this fails        to identify the target device, a candidate set of devices which        have no history of previous association may be used        subsequently.        As described above, these filter criteria may in addition, or        instead, be used to determine the order in which devices within        the candidate set are triggered (in block 104).

As described above, the initiator device comprises a light source 205that is capable of displaying an optical indicator, such as a lightpattern. This optical indicator may be a flash of a single color or maybe a more complex or detailed pattern and various examples are describedbelow. Most computing devices include a display (such as an LCD) and inmany examples the light source 205 may be a display. Use of a displayenables complex optical indicators (e.g. complex patterns) to be used,and where the location of the target device on the display is known, theoptical indicator can be targeted at the target device. However, in someexamples, the light source may comprise one or more LEDs. A light guideand diffuser may be used, in some implementations, to spread the lightemitted by the one or more LEDs in order that the target device does notneed to be accurately positioned with respect to the light source. Inanother example, the light source may comprise a projector.

As described above, the optical indicator used may be dependent on thelight source used to produce the optical indicator and on whether thelocation (or an approximate location) of the target device is known.Where the light source comprises one or more LEDs, the optical indicatormay comprise one or more flashes of a single color of light or of asequence of colors. Where the light source comprises a display, thedisplayed image (which is the optical indicator) may be a single color(over the entire display), a region of color (as in the red circleexample described above), an icon or other pattern. In most embodiments,the optical indicator used is relatively simple such that it does notrequire the target device to focus. This is particularly relevant wherethe light sensor is a camera device and the target device is placed incontact with (or close to) the light source (e.g. on the display). Insuch a situation, the camera may not be able to focus on the opticalindicator. In other examples, the light sensor may not be provided withmeans for focusing. In further examples, however, the optical indicatormay be a more detailed pattern or icon.

Where the light source is a display and the location of the targetdevice is known, the optical indicator may comprise a region of colordisplayed underneath the target device. As the location of the camerawithin the target device may not be known, the region may need to be asbig as the detected shape and size of the target device. Furthermore, asthe detected shape and size of the target device may be dependent on thedetection technology used, the detected shape may not be the whole shapeof the device (e.g. reflective IR will not detect matt black portions ofa mobile device), the region of color displayed may be larger than thedetected shape and size of the target device.

A display may also be used to display a sequence of colors or otherchanging pattern (as the optical indicator) and where the location ofthe target device is not known, an optical indicator may be displayedwhich enables the initiator device to determine an approximate location.A simple example of such an optical indicator is shown in FIG. 4 whichshows three successive images which may be displayed. In the firstimage, 401, the whole screen is red, in the second, 402, the screen isbisected vertically into a red half and a blue half and in the third,403, the screen is bisected horizontally into a red half and a bluehalf. If the target device is triggered to perform light detection(block 302) three times or for a period of time covering the display ofthe sequence of three images, the target device can be located withinone of the four quadrants of the display depending on the detectedsequence of colors (e.g. all red is top left quadrant). In otherexamples, bars of colors may be displayed which move across the screen,as shown in FIG. 5. In this example, two bars 501, 502 of differentcolors may be displayed, one of which traverses horizontally (bar 502,as indicated by the arrow) and one of which traverses vertically (bar501, as indicated by the arrow). The signal detected by a candidatedevice may be used to determine when and if the bars were visible usingthe light sensor and from this the target device, and its location, canbe identified.

Another example of an optical indicator which may be used is a highintensity spot which may be scanned across the display. In this example,the target device may determine the time at which the bright spot wasdetected by the light sensor and this information may be used by theinitiator device to determine the location of the target device withrespect to the display area (in addition to identifying the targetdevice from the candidate set of devices). The timing information mayalso enable the initiator to distinguish between multiple devices in thecandidate set which have a light sensor which can image the display,e.g. two wireless enabled devices which are placed on an interactivesurface. These multiple devices may each be target devices, oralternatively, only one may be a target device.

The optical indicator displayed may be the same each time the method isperformed or different optical indicators may be used each time. Forexample, the color displayed (e.g. in a circle on the display where thetarget device is located) may be selected substantially at random. Thismay be useful where there are two initiator devices within wirelessrange of each other so that if they both initiate the method at the sametime, they display different optical indicators and hence it is possibleto distinguish between target devices for each initiator device.Alternatively, the two initiator devices may be synchronized orotherwise communicate such that only one initiator device displays anoptical indicator at any one time.

Whilst the above description refers to use of visible light anddifferent colors in displaying the optical indicator in other examples,IR light (e.g. bright IR) may be used or grayscale light patterns may beused. Different wavelengths within the IR band may also be used.

Although the above description refers to optical indicators which may bedynamically displayed by the initiator device (i.e. is displayed for ashort period of time), in other examples the optical indicator displayedmay be static and may be displayed continuously or for long periods oftime. In an example, the optical indicator may be provided by a fixeddisplay (e.g. an advertising billboard). Where the light sensor is acamera, the fixed display need not be backlit, however if target devicesare used which comprise photodetectors, the fixed display requires rearillumination.

As described above, the target device comprises a light sensor 207,which comprises a device that is capable of detecting one or moreproperties of the optical indicator displayed by the initiator device.Many computing devices include a digital camera and this may be used asthe light sensor 207. In other examples, a photodetector may be used asa light sensor. Where the target device includes an optical fingerprintreader, the sensor in this reader may be used as the light sensor 207.An optical fingerprint reader may also be used as a light source whereincluded in an initiator device. The light sensor may captureinstantaneous data (e.g. a still image) or a may capture a stream ofdata over a short period of time (e.g. a short video).

The triggering of light detection (in block 302) may be dependent uponsensor information or other conditions within a candidate device suchthat not all candidate devices receiving a trigger signal (in block 301)may actually detect light (in block 302). For example, where theinitiator device knows the orientation of the target device (e.g. in aninteractive surface example, the initiator device knows that the deviceis horizontal), the trigger message may indicate that devices which arenot horizontal (as determined by sensors within the candidate devices)should not detect light or should ignore the trigger message. In anotherexample, a candidate device may only implement the trigger message anddetect light if its keypad lock is off. Use of sensor data or otherconditions may therefore be used to reduce the number of candidatedevices, other than the target device, which detect light (e.g. capturean image) and send data representative of the detected signal back tothe initiator device.

As shown in FIG. 3, the target device (or any other device in thecandidate set) is triggered to detect light using any available lightsensor (block 302), typically using a camera within the target device.The data which is then communicated back to the initiator device (inblock 303) may comprise the raw sensor data (e.g. the image captured bythe camera) or the data may first be processed. Examples of processingwhich may be performed include: determination of the color (or sequenceof colors) detected, determination of the time at which a color orcolors are detected, determination of the intensity of light detectedetc. In the simple example used above, the target device may send theinitiator device an image file which comprises a red image (from the redcircle) or the target device may process this image and send dataindicated that the detected image was red to the initiator device. Inanother processing example, the target device may reduce the size of theimage to a few pixels (e.g. 1-10 pixels).

Whilst the raw data may provide the initiator device with moreinformation, there may be privacy concerns where the raw data is animage captured using a digital camera. In such an instance, processingthe data on the target device alleviates any privacy concerns. Use offilters on the candidate set or filters within the trigger conditions,as described above, may also alleviate privacy concerns, e.g. byfiltering out devices which are not in the correct orientation and/ordevices which are in motion.

In some examples, the target device may not comprise a light sensor. Insuch a situation, the target device may use user input to characterizethe optical indicator. For example, where the optical indicator is acolored circle displayed on a surface around the target device, the usermay be presented with a number of color options (e.g.Blue/Red/Green/none). The user selects the color of the circle whichsurrounds the device and provides the corresponding input to the targetdevice. This selection may then be communicated to the initiator device.In another example, the user may be asked to confirm that they saw acolor (rather than selecting a particular color).

The identification of the target device (in block 106) from the dataprovided by members of the candidate set may be performed by comparingthe data received and the optical indicator displayed. Using the exampleabove, where the optical indicator was a red circle, the match betweenthe displayed and detected colors may be measured and any candidatedevice detecting red is possibly the target device. Where more than onedevice detected red, a second optical indicator may be displayed (e.g. acircle of a different color) and the process repeated.

A number of different examples are described below with reference toFIGS. 6-12. These examples show different types of initiator and targetdevices which may be used and different applications for the methodsdescribed above. It will be appreciated however, that these are justsome of the possible embodiments, and aspects of any of the examples maybe combined with other examples to provide further embodiments.

FIG. 6 shows an example in which the initiator device is an interactivesurface 601 and an example method of operation is shown in FIG. 12. Theinteractive surface may be touch sensitive and therefore is able todetect one or more wireless enabled devices 602, 603 when they areplaced on the surface (block 1201). The interactive surface determines acandidate set of wireless devices (block 1202). This may comprise allthe wireless devices which are in range, or the list of all the wirelessdevices in range may be filtered in some way to provide the candidateset (as described above). The interactive surface then displays anoptical indicator on its display, such as a region 604 of a particularcolor underneath the target device (block 1203). The interactive displaycommunicates with each of the devices in the candidate set to triggerimage capture (or other form of light detection) by the devices (block1204). As described above, a device from the candidate set may eithersend the captured data (e.g. the captured image) or other datarepresentative of the captured data (e.g. the color seen) back to theinteractive surface (received in block 1205). The target device 602 canthen be identified by matching the detected color (as determined fromthe data received in block 1205) to the particular color displayed(block 1206). If more than one of the candidate devices detected theparticular color, the process (blocks 1203-1206) can be repeated toenable unique identification of the target device. For example, theinteractive display may display a second optical indicator comprising acircle of a different color and the size of the circle may be smaller toreduce the chance of it being seen by more than one device. Where thereis more than one target device (e.g. devices 602 and 603), the process(e.g. blocks 1203-1206 or the entire process) may then be repeated forthe other target device 603. Alternatively, the two target devices maybe identified in parallel by displaying, for example, two circles ofdifferent colors, one under each target device (in block 1203).

In another example, the initiator device may comprise a display which isnot touch sensitive (e.g. an LCD monitor). In such an example, theproximity detection (in block 101) may be performed using wirelessdiscovery techniques, using a camera or any other suitable technique.For example, IR emitters and receivers may be placed around the edge ofa display and presence may be detected when the IR beam from atransmitter to a receiver is broken by the presence of an object.Alternatively, the process may be triggered by a user (e.g. pressing abutton on the initiator device) which results in the initiator deviceidentifying a candidate set of devices in proximity (block 102). Wherethe display is not touch sensitive the initiator device may not have anylocation information to enable it to tailor the optical indicatordisplayed (in block 103) to the position of the device requiringidentification. The initiator device may therefore display an opticalindicator which comprises a whole screen of a particular color or asequence of colors etc. Where a sequence of colors is used, the devicesin the candidate set may be triggered to perform a sequence of detectionoperations (e.g. to capture multiple still images) or to detect thelight for a period of time (e.g. to capture a video image) and this datamay be used to uniquely identify a wireless device which is in proximityto the initiator device and which can view all of, or a part of, thedisplay. This device which is identified is the target device. Dependenton the optical indicator used, the location of the target device withrespect to the display may also be determined (e.g. as described abovewith reference to FIGS. 4 and 5).

In another example, the light source may be a projector which projectsthe optical indicator (in block 103). The optical indicator may bedetected directly by the target device (in block 302), i.e. by theprojector shining onto the light sensor, or alternatively the targetdevice may detect the optical indicator once projected onto a surface(e.g. a wall or a ceiling). Projection of an optical indicator onto theceiling may enable identification of a target device which is placed ona surface with its camera face up, rather than the face downconfiguration as shown in FIG. 6.

FIG. 7 shows an example in which the initiator device comprises aspecial pad 701 which may be used for synchronizing devices. This padmay be a peripheral device for a computing device. The pad comprises alight source 702 which may, for example, comprise a multi-color LED, orone or more single color LEDs. The pad may be able to detect anotherdevice 703 (the target device) placed on its surface using any suitabletechnique, such as an IR proximity sensor 704. Alternatives to aproximity sensor include, but are not limited to, a pressure switch, acontact sensor and a light sensor. Alternatively a button may beprovided for a user to push when placing a device on the pad.

The pad uses the method of FIG. 1 to distinguish the target device 703which is on the pad from any other wireless enabled devices which may bewithin wireless range of the pad. The optical indicator is produced (inblock 103) by the light source 702 and is detected (in block 302) by alight sensor 705 (e.g. a camera or photodetector) in the target device703. In order to increase the size of the optical indicator which isproduced by the one or more LEDs (or other sources) within the pad, alight guide and a diffuser may be used. This removes any requirement toplace a device in a particular location on the pad. The pad may be usedfor other functions, in addition to synchronizing devices, such as amouse mat and/or for charging the target device 703 using inductivecharging techniques. Where the pad includes an optical fingerprintsensor, this may be used for proximity sensing and/or displaying theoptical indicator.

In a variation on that shown in FIG. 7, the situation may be invertedsuch that the pad 701 is the target device and includes a light sensorand the device placed on the pad 703 is the initiator device andincludes a light source. For example, the pad may comprise aphotodetector and the initiator device may be a mobile telephone withthe display used as the light source.

FIGS. 8 and 9 show two examples where the initiator device is a mobilecomputing device, such as a mobile telephone. The methods describedabove may be used to pair the device with another mobile device (asshown in FIG. 8) or with a non-mobile device, such as a desktop PC (asshown in FIG. 9).

FIG. 8 shows two mobile devices 801, 802, each comprising a camera 803and a display 804. The two devices are held together such that thecamera of the target device 802 is in front of the display of theinitiator device 801. The display of the initiator device is used todisplay an optical indicator (block 103), which may comprise a screen ofa single color, and this is detected by the camera of the target device(block 302). Other devices in the candidate set will be unlikely to beable to detect the optical indicator which is displayed by the initiatordevice as it is mainly obscured by the target device, although if thereis any uncertainty (e.g. because two candidate devices detect the colordisplayed on the initiator device), a second optical indicator may bedisplayed by the initiator device.

FIG. 9 shows a mobile device 901 (the initiator device) and a non-mobiledevice 902 (the target device), which comprises a camera 903. In thisexample, the non-mobile device comprises a desktop PC and the camera isa web-cam. A display 904 on the mobile device 901 is used to display anoptical indicator (block 103) which is detected by the camera 903 (block302).

FIG. 10 illustrates various components of an exemplary computing-baseddevice 1000 which may be implemented as any form of a computing and/orelectronic device, and which may comprise an initiator device.Computing-based device 1000 comprises one or more processors 1001 whichmay be microprocessors, controllers or any other suitable type ofprocessors for processing computing executable instructions to controlthe operation of the device in order to identify a target device (andperform any subsequent pairing or synchronization etc).

Platform software comprising an operating system 1005 or any othersuitable platform software may be provided at the computing-based deviceto enable application software to be executed on the device. Theapplication software may comprise: a discovery module 1006, arranged toidentify a candidate set of devices, an identification module 1007,arranged to identify the target device from those in the candidate setbased on the data received from each device, and a display driver 1008,arranged to generate the optical indicator and cause it to be displayed.

The computer executable instructions may be provided using anycomputer-readable media, such as memory 1004. The memory is of anysuitable type such as random access memory (RAM), a disk storage deviceof any type such as a magnetic or optical storage device, a hard diskdrive, or a CD, DVD or other disc drive. Flash memory, EPROM or EEPROMmay also be used.

The device further comprises a wireless transceiver 1002 (or separatewireless transmitter and receiver modules) and a light source 1003 whichis used to display the optical indicator generated by the display driver1008. As described above, the optical indicator generated may be uniformlight of a single color, a region of color, a sequence of colors, adynamic pattern, scanning spots/lines, a detailed pattern etc.

FIG. 11 illustrates various components of an exemplary computing-baseddevice 1100 which may be implemented as any form of a computing and/orelectronic device, and which may comprise a target device.Computing-based device 1100 comprises one or more processors 1101 whichmay be microprocessors, controllers or any other suitable type ofprocessors for processing computing executable instructions to controlthe operation of the device in order to identify a target device (andperform any subsequent pairing or synchronization etc).

Platform software comprising an operating system 1105 or any othersuitable platform software may be provided at the computing-based deviceto enable application software to be executed on the device. Theapplication software may comprise: an image capture module 1106,arranged to capture the signal detected by the light sensor when atrigger is received from an initiator device, and an image processingmodule 1107, arranged to process the detected signal and generate therepresentative data which can be sent to the initiator device.

The computer executable instructions may be provided using anycomputer-readable media, such as memory 1104. The memory is of anysuitable type such as random access memory (RAM), a disk storage deviceof any type such as a magnetic or optical storage device, a hard diskdrive, or a CD, DVD or other disc drive. Flash memory, EPROM or EEPROMmay also be used. The device further comprises a wireless transceiver1102 (or separate wireless transmitter and receiver modules) and a lightsensor 1103.

It will be appreciated that only those components of the computingdevices 1000 and 1100 which are necessary for the description of aninitiator device and a target device respectively and their operationare shown in FIGS. 10 and 11. The computing devices 1000 and 1100 maycomprise other elements, such as one or more inputs (e.g. which are ofany suitable type for receiving media content, Internet Protocol (IP)input, etc), a communication interface, one or more outputs (such as anaudio and/or video output to a display system integral with or incommunication with the computing-based device), etc.

The methods described above enable an initiator device to uniquelyidentify a target device from a set of wireless devices which are withinrange of the initiator device. This may be useful for automaticidentification of wireless devices or where there are large numbers ofwireless devices within range and therefore it may be difficult toidentify the target device using other means (e.g. the list of devicespresented to a user might be unfeasibly large).

The methods also, in many embodiments, do not require any user input andcan therefore be performed automatically. This may be useful in manyapplications, including where mobile devices (such as mobile telephones)are used as payment tools. For example, a user may hold their mobiletelephone up to a ticket machine or kiosk etc in order to purchase anitem (e.g. a ticket). The ticket machine needs to uniquely identify themobile telephone which is being used for the transaction from all thosein the vicinity and the methods described herein may be used. In anexample, a synchronization pad (as shown in FIG. 7) or any display onthe ticket machine may be used to provide the optical indicator.

The methods described herein may be used to enable users to connect topublic displays to receive, transmit or share data. In such an example,the public display may be the initiator device and the method may betriggered by holding a mobile device against a defined portion of thedisplay, pressing a button on the display, SMS messaging a numberdisplayed on the display etc. The public display may have a definedregion where it displays the optical indicator for use in pairing ofdevices.

In a further example application, the initiator device may be a digitalphotograph frame. Use of this method may enable association between theframe and a camera device (which may be a mobile telephone or otherdevice which includes a camera). The association may enable automatictransfer of images to the digital photograph frame and this transfer maybe automatic (e.g. on proximity sensing of the camera device) or mayrequire user input (e.g. pressing a button on the frame to trigger themethods described above).

Having used the methods described above to associate an initiator deviceand a target device, the methods may further be used to track movementof the target device with respect to the initiator device and/or toprovide inputs to the initiator device. FIG. 13 shows a method oftracking movement and/or determining user input. The initiator devicedisplays a light pattern (block 1301) which may be the same as theoptical indicator as described above (and therefore may be acontinuation of block 103) or may be different (e.g. a new light patternwhich is displayed). Examples of light patterns are described below withreference to FIG. 14. The target device detects the light pattern (block1302) and sends data representative of the detected signal to theinitiator device (block 1303). The detection (in block 1302) is similarto the detection described above and may be triggered by the initiatordevice (e.g. as a result of the trigger message generated in block 104or a subsequent trigger message sent only to the target device). Anyprocessing performed on the detected data before sending it to thetarget device may be similar to that described above in (in relation toFIG. 3). The data received by the initiator device is then analyzed todetermine the motion of the target device and/or to identify a userinput (block 1404). The user input may be determined directly from thedetected signal (e.g. a particular color detected may be mapped to aparticular input) or the user input may be determined from thedetermined motion (e.g. a particular movement may be mapped to aparticular user input).

FIG. 14 shows two example light patterns which may be displayed by theinitiator device in order to detect motion of the target device and/orto provide a user input. A first example 1401 shows a grid of squareswhich may be different colors (e.g. black and white) or differentintensities. When a target device is moved relative to the light pattern(e.g. as indicated by arrow 1403), the detected signal changes and fromthis the movement of the target device can be determined. The secondexample 1401 shows a circular pattern with a red centre and four outerregions of different colors. When a target device is moved, the detectedcolor changes (e.g. from red to blue when moved as indicated arrow 1404)and from this color change the motion and/or a user input can bedetermined. As described above, any light pattern may be displayeddynamically or may be fixed.

Where the location of the target device is known (e.g. in theinteractive surface example), the light pattern displayed (in block1301) may be located accordingly. In the interactive display example,the light pattern may be displayed underneath the target device. Whenmotion is detected, the position of the light pattern may stay the sameor alternatively, once motion has been detected the position of thelight pattern may be updated to remain in the same (approximate)position relative to the target device. For example, the second pattern1402 shown in FIG. 14 may be tracked with the position of the targetdevice such that motion of the target device always results in a colorchange from red to one of the other colors displayed (e.g. red to blue,green, yellow or black).

The methods described above with reference to FIGS. 13 and 14 enable amobile device, such as a mobile telephone, to be used to provide asimple mouse (or other pointing device) replacement.

Having used the methods described above to associate an initiator deviceand a target device, the methods may be used to locate the image sensoron the target device. This may be particularly applicable to situationswhere the initiator device has location information relating to thetarget device itself from the proximity sensing (in block 101), e.g.when using a touch sensitive surface. By changing the optical indicatordisplayed and analyzing data representative of the detected data (in asimilar manner to that shown in FIG. 13 and described above) a moreprecise location of the image sensor can be identified. For example,where initially a colored region is used, the size of the region may bemade gradually smaller until it can no longer be detected by the targetdevice, or the region may be gradually moved until it can no longer bedetected by the target device. This may be repeated to further reducethe margin of uncertainty in the position information. This positioninformation may be stored along with the wireless identifier (oraddress) of the target device for future use.

Having identified a more precise location of the image sensor, thisinformation may be used in many ways. In a first example, where themotion of the target device is subsequently used to track the deviceand/or provide user input, the location information may be used toposition the light pattern displayed (in block 1301). This may, forexample, enable a light pattern to be displayed which is not visible tothe user (because it is small and obscured by the target device) andhence does not distract the user. In another example, this may enableidentification of the type of the target device (e.g. the make and modelof a mobile telephone) through use of a database or look-up tablerelating detected shape and size of the target device, the relativeposition of the image sensor and the device type. In another example,transmitters within the initiator device may be used to transmit dataoptically to the target device. The optical signal can be directed atthe image sensor directly which provides a more secure link (as thirdparties cannot intercept the signal) and does not distract the user.

Although the present examples are described and illustrated herein asbeing implemented using Bluetooth or WiFi, the system described isprovided as an example and not a limitation. As those skilled in the artwill appreciate, the present examples are suitable for application in avariety of different types of wireless systems.

The term ‘computer’ is used herein to refer to any device withprocessing capability such that it can execute instructions. Thoseskilled in the art will realize that such processing capabilities areincorporated into many different devices and therefore the term‘computer’ includes PCs, servers, mobile telephones, personal digitalassistants and many other devices.

The methods described herein may be performed by software in machinereadable form on a tangible storage medium. The software can be suitablefor execution on a parallel processor or a serial processor such thatthe method steps may be carried out in any suitable order, orsimultaneously.

This acknowledges that software can be a valuable, separately tradablecommodity. It is intended to encompass software, which runs on orcontrols “dumb” or standard hardware, to carry out the desiredfunctions. It is also intended to encompass software which “describes”or defines the configuration of hardware, such as HDL (hardwaredescription language) software, as is used for designing silicon chips,or for configuring universal programmable chips, to carry out desiredfunctions.

Those skilled in the art will realize that storage devices utilized tostore program instructions can be distributed across a network. Forexample, a remote computer may store an example of the process describedas software. A local or terminal computer may access the remote computerand download a part or all of the software to run the program.Alternatively, the local computer may download pieces of the software asneeded, or execute some software instructions at the local terminal andsome at the remote computer (or computer network). Those skilled in theart will also realize that by utilizing conventional techniques known tothose skilled in the art that all, or a portion of the softwareinstructions may be carried out by a dedicated circuit, such as a DSP,programmable logic array, or the like.

Any range or device value given herein may be extended or alteredwithout losing the effect sought, as will be apparent to the skilledperson.

It will be understood that the benefits and advantages described abovemay relate to one embodiment or may relate to several embodiments. Theembodiments are not limited to those that solve any or all of the statedproblems or those that have any or all of the stated benefits andadvantages. It will further be understood that reference to ‘an’ itemrefers to one or more of those items.

The steps of the methods described herein may be carried out in anysuitable order, or simultaneously where appropriate. Additionally,individual blocks may be deleted from any of the methods withoutdeparting from the spirit and scope of the subject matter describedherein. Aspects of any of the examples (whether methods, apparatus orotherwise) described above may be combined with aspects of any of theother examples described to form further examples without losing theeffect sought.

The term ‘comprising’ is used herein to mean including the method blocksor elements identified, but that such blocks or elements do not comprisean exclusive list and a method or apparatus may contain additionalblocks or elements.

It will be understood that the above description of a preferredembodiment is given by way of example only and that variousmodifications may be made by those skilled in the art. The abovespecification, examples and data provide a complete description of thestructure and use of exemplary embodiments of the invention. Althoughvarious embodiments of the invention have been described above with acertain degree of particularity, or with reference to one or moreindividual embodiments, those skilled in the art could make numerousalterations to the disclosed embodiments without departing from thespirit or scope of this invention.

1. A method of identifying a target device in proximity to a firstdevice, the method comprising: identifying a candidate set of devices;displaying an optical indicator; sending a message to at least onedevice from the candidate set of devices, said message being arranged totrigger light detection on said device; receiving data from at least onedevice from the candidate set in response to said messages, the databeing representative of a detected signal on said device; anddetermining if a device from the candidate set is the target devicebased on the data received from said device and the optical indicatordisplayed.
 2. A method according to claim 1, wherein identifying acandidate set of devices comprises: using a wireless discovery protocolto identify a candidate set of devices within range of the first deviceand wherein each of the candidate set of devices is identified by awireless identifier.
 3. A method according to claim 2, whereinidentifying a candidate set of devices further comprises: filtering thecandidate set of devices based on defined criteria.
 4. A methodaccording to claim 1, wherein said message is arranged to trigger imagecapture on said device.
 5. A method according to claim 4, wherein saiddata received from at least one device comprises one of a captured imageand data generated from a captured image.
 6. A method according to claim1, wherein the method further comprises, prior to identifying acandidate set of devices: detecting a target device in proximity to thefirst device.
 7. A method according to claim 1, further comprising:repeating the sending, receiving and determining steps until a devicefrom the candidate set is identified as the target device.
 8. A methodaccording to claim 1, wherein said first device comprises an interactivesurface and said target device comprises a device placed on theinteractive surface and wherein displaying an optical indicatorcomprises: displaying a region of color on the interactive surfaceproximate to the target device.
 9. An apparatus comprising: a lightsource arranged to display an optical indicator; a wireless transmitterand receiver module; a processor; a discovery module arranged toidentify a set of wireless devices within range of the apparatus, eachdevice having a wireless identifier; and an identification modulearranged to send a message to each of the set of wireless devices totrigger light detection by the device, to receive data representative ofa detected signal from a wireless device and to determine the wirelessidentifier of a device in close physical proximity to the light sourceusing said data.
 10. An apparatus according to claim 9, wherein theidentification module is arranged to determine the wireless identifierof the device in close proximity by determining if said data correspondsto the displayed optical indicator.
 11. An apparatus according to claim9, wherein the light source comprises a touch sensitive display, andwherein said device in close physical proximity to the light sourcecomprises a device in contact with said display.
 12. An apparatusaccording to claim 11, wherein the touch sensitive display is arrangedto detect a position of said device in contact with said display andwherein said optical indicator is dependent on said position.
 13. Anapparatus according to claim 9, wherein the light source is locatedwithin a peripheral device and the peripheral device further comprises aproximity sensor.
 14. An apparatus according to claim 13, wherein thediscovery module is arranged to identify said set of devices in responseto detection of said device in close physical proximity using saidproximity sensor.
 15. An apparatus according to claim 13, wherein thelight source comprises one or more LEDs.
 16. One or more tangibledevice-readable media with device-executable instructions for performingsteps comprising: in response to receipt of a trigger message from adevice, detecting light using a light sensor; and sending datarepresentative of the detected light to said device.
 17. One or moretangible device-readable media according to claim 16, wherein the lightsensor comprises a camera and wherein detecting light using a lightsensor comprises: capturing at least one image using said camera. 18.One or more tangible device-readable media according to claim 17,wherein said at least one image comprises at least one unfocussed image.19. One or more tangible device-readable media according to claim 17,further comprising device-executable instructions for performing stepscomprising: processing said image to generate said data.
 20. One or moretangible device-readable media according to claim 19, wherein said datacomprises a color of said image.